Tonight’s “Saturday Night Live” season finale was notable for its final appearances by a number of soon-to-be-former castmembers, including, in all likelihood, Fred Armisen, who reprised his Ian Rubbish punk character with a live band that included Sonic Youth’s Kim Gordon, Steve Jones of the Sex Pistols, Dinosaur Jr’s J Mascis, “Portlandia” co-star and former Sleater-Kinney member Carrie Brownstein, and husband-and-wife duo Aimee Mann and Michael Penn.